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TSRC, Tob. Sci. Res. Conf., 2013, 67, abstr. 10

Organic acid inhibiting germination and growth of tobacco seed and soil microbial community.

WANG Maosheng; WANG Hancheng
Guizhou Academy of Tobacco Science, Guizhou, P.R. China

Root exudates containing root-specific metabolites have critical ecological impacts on soil macro and microbiota as well as on the whole plant itself. Organic acids, as the most important component in plant root exudates, have been reported to accumulate in the continuous cropping system of tobacco. The aim of the present investigation was to assess their phytotoxic effects on the whole process of the flue-cured tobacco seedling. The germination experiments of tobacco seeds in organic acids including benzoic, p-hydroxybenzoic, salicylic and malic acids were conducted. The results showed that p-hydroxybenzoic and malic acids did not affect the germination rate, while the germination rate decreased with the concentration increase of benzoic and salicylic acids. Tobacco seedlings were grown in Hoagland nutrient solution with benzoic, p-hydroxybenzoic, salicylic and malic acids at concentration of 0, 100, 200, 400, 600 and 800 ?M respectively. The dry and fresh weights of the whole plant showed increase firstly and decreased afterward with the concentration increase of benzoic, p-hydroxybenzoic and salicylic acids. The malic acids did not affect the dry and fresh weights of the plant. The microbial number of soil actinomyces was decreased with the concentration increase of benzoic and p-hydroxybenzoic acids, and increased firstly and decreased afterward with the concentration increase of salicylic and malic acids. The microbial number of soil fungus was decreased with the concentration increase of benzoic, p-hydroxybenzoic, salicylic and malic acids. The microbial number of soil bacteria in different treatments of salicylic and malic acids, and the trend of which in different of Benzoic and p-hydroxybenzoic were first increased and then decreased.